The present invention relates to a stator having segment coils and a motor including the stator.
A stator described in Japanese Laid-Open Patent Publication No. 11-98788 includes segment coils configured by electrically connecting a plurality of segment conductors together. The segment conductors are segment conductor coils (SC coils). The teeth of the stator are formed such that the slot width, which is the dimension of each slot in a direction perpendicular to the radial direction, becomes uniform in the radial direction. In each of the slots, linear portions of segment conductors are radially aligned. Each of the linear portions has a rectangular cross section. By arranging the segment conductors (the linear portions) regularly in each slot, the space factor of the slot is improved. As a result, the stator ensures a highly efficient motor.
However, as viewed in a cross section perpendicular to the axial direction of the stator, the tooth width, which is the tooth thickness in the direction perpendicular to the radial direction, becomes greater in the radially outward direction. The stator thus increases radial direction dependence of magnetic resistance in each tooth. This excessively increases magnetic resistance, or, in other words, magnetic flux density, at an inner position in the radial direction of the tooth. As a result, the rotor is prevented from smoothly rotating.
Accordingly, it is an objective of the present invention to decrease radial variation of magnetic resistance in teeth in a stator and a motor having segment coils.